use less stack on number print

Author: DEvil0000

Diff for: cores/arduino/Print.cpp

@@ -202,10 +202,7 @@ size_t Print::println(const Printable& x)
 
 size_t Print::printNumber(unsigned long n, uint8_t base)
 {
-  char buf[8 * sizeof(long) + 1]; // Assumes 8-bit chars plus zero byte.
-  char *str = &buf[sizeof(buf) - 1];
-
-  *str = '\0';
+  size_t written = 0;
 
   // prevent crash if called with base == 1
   if (base < 2) base = 10;
@@ -214,10 +211,11 @@ size_t Print::printNumber(unsigned long n, uint8_t base)
     char c = n % base;
     n /= base;
 
-    *--str = c < 10 ? c + '0' : c + 'A' - 10;
+    c = (c < 10 ? c + '0' : c + 'A' - 10);
+    written += write(&c, 1);
   } while(n);
 
-  return write(str);
+  return written;
 }
 
 size_t Print::printFloat(double number, uint8_t digits)